1. Field of Invention
The invention relates to lasers and, more particularly, to lasers having a distributed structure. Such lasers have excellent amplification characteristics and a very large wavelength selectivity, the wavelength of the emitted radiation being directly linked to the grid spacing.
The invention is more particularly concerned with a laser device having a multiple distributed structure capable of emitting radiations of different wavelengths in the spontaneous emission band of the semiconductor, such radiations of different wavelengths being emitted sequentially or simultaneously, as desired.
2. Prior Art
A semiconductor laser structure capable of emitting a laser radiation having two or more wavelengths is well known in the art. This well known structure comprises, integrated on the same substrate, a plurality of lasers having distributed resonators. Each laser includes a distributed resonator having the proper spacing for emission in accordance with a specified wavelength. The paths of the stimulated emission are parallel, as are the grooves of the different gratings. At the ends the radiations to be combined are brought together and guided by an optical fiber, the wavelengths being combined with one another in sequence.
This type of structure leaves unetched intermediate regions on the substrate and requires the etching of a plurality of separate gratings having different spacings; the excitation means can be shared by the different lasers, but is necessary to provide guide areas in order to bring together the emitted radiations of different wavelengths.